Methyl jasmonate is blowing in the wind, but can it act as a plant-plant airborne signal?

Interplant communication in nature is beginning to took like a reality with the field demonstration that tobacco plants downwind of damaged sagebrush suffer less herbivory, a response that appears to be mediated by an airborn e signal. Sagebrush constitutively releases methyl jasmonate (MeJA), a comp ound that is highly active in inducing a number of physiological responses in plants. Damage increases the absolute quantity of the MeJA released as w ell as the proportion of MeJA in the isomeric cis form. Several studies hav e shown that volatile MeJA, when released in sufficient quantities, can sim ulate responses elicited by direct MeJA applications, Additionally. the the rmodynamically unstable eis isomer, which is responsible for the characteri stic jasmine odor, is thought to be the biologically active form of MeJA. T o examine the hypothesis that the cis-MeJA release is responsible for the a pparent interplant communication, we developed methods to: (1) entrain sage brush constituents in water which preserved the isomeric shift in the MeJA released after damage; (2) chemically manipulate the MeJA trans: cis ratio, and (3) isolate nearly pure cis-MeJA by HPLC. These treatments were applie d as aqueous sprays to a natural population of tobacco plants. however, an outbreak of specialist herbivores consumed all treated plants and chemical analysis on previously harvested treated leaf material was inconclusive. Th e hypothesis is currently being carefully investigated with laboratory expe riments. (C) 2001 Elsevier Science Ltd. All rights reserved.